1. Field of the invention
The present invention relates to an elastic sheet used in a switch, and particularly to a sheet switch applied in mobile phone or the likes.
2. Description of Related Art
A conventional sheet switch using an elastic sheet 4′ is disclosed in FIGS. 1-2. The elastic sheet 4′ for connecting with a circuit board 5′ comprises a first sheet 10′ having a metal sheet 11′ thereon, a plurality of moveable contacts 20′ attached to a bottom surface of the first sheet 10′ and a separate sheet 30′. The separate sheet 30′ is affixed to a lower surface of the first sheet 10′ by adhesive 32′ smeared on an upper surface thereof. The first sheet 10′ has a bending portion 12′ bending toward the circuit board 5′ along the line II-II for contacting a ground end 53′ formed on an upper surface of the circuit board 5′.
The elastic sheet switch comprises the elastic sheet 4′ and the circuit board 5′. Before assembling of the elastic sheet 4′ and the circuit board 5′, the separate sheet 30′ is peeled off from the bottom surface of the first sheet 10′. The bending portion 12′ of elastic sheet 4′ is attached to the ground end 53′ for discharging electrostatic charges accumulated on the first sheet 10′. The circuit board 5′ has a plurality of fixed contacts 50′ each having a central fixed contact 52′ and an outer fixed contact 51′ encircling around, but insulated from, the central fixed contact 52′. A fringe portion of each moveable contact 20′ abuts against the outer fixed contact 51′. A center portion 21′ of the moveable contact 20′ is separated from the central fixed contact 52′. The center portion 21′ is capable of being depressed downwardly for contacting with the central fixed contact 52′. The outer fixed contact 51′ and the center fixed contact 52′ are therefore electrically connected via the moveable 20′.
However, when the bending portion 12′ is connected to the ground end 53′, the bending portion 12′ is apt to damage by electrostatic discharge.
Hence, an improved sheet switch is desired to overcome the disadvantages of the prior art.